Our goal is to characterize high energy phosphorus and phospholipid metabolism of the brain in HIV disease. We will utilize in vivo Magnetic Resonance Spectroscopy (MRS) to study HIV seropositive patients who range from normal neuropsychiatric function to full-blown AIDS Demential Complex (ADC). In our pilot study, we found a decrease in the adenosine triphosphate (ATP) in inorganic phosphate (Pi) and phosphocreatine (PCr) to Pi ratios in HIV-infected patients (mostly AIDS/ARC) compared to control subjects and a negative correlation between ratios and degree of neuropsychiatric impairment within the patient group. We will determine whether MRS measures of in vivo brain phosphors and phospholipid metabolism differ in HIV infected individuals compared to HIV negative controls and if HIV related changes in these measures are associated with the presence and/or degree of neuropsychiatric impairments. We will also determine whether the in vivo brain metabolic changes associated with ADC are specific to ADC or are general findings reflective of subcortical dementia and if particular in vivo brain metabolic changes in ADC are specific to white matter or subcortical grey matter. Finally we will determine whether changes in neuropsychiatric status in HIV disease (either as a result of disease progression or positive treatment response) are associated with changes in MRS measures of phosphorus and phospholipid metabolism.